DeNA Co., Japan’s biggest social- gaming operator, rose the most in more than two years in Tokyo trading after saying it will spend as much as 20 billion yen ($254 million) buying back up to 10 percent of its stock.

In 2010, Masayoshi Son, the billionaire founder of Softbank Corp., laid out a plan for the next 300 years. For a start, he would invest in 5,000 companies by 2040, giving his unborn successors a base to build on.

Yoshikazu Tanaka, Japan’s youngest billionaire and founder of Gree Inc., lost $704 million in the past two days after his social-gaming company declined on concerns one of its sales methods may be declared illegal.